Piston



J. M. SHIMER Dec. 11, 1934.

PISTON Filed Oct. 20, 1931 2 Sheets-Sheet l Dec. 11, 1934. J. M. SHI'MER 1,933,780

' PISTON Filed Oct. 20, 1951 2 Sheets-Sheet 2- INVENTOR M Sim w win Patented Dec. 11, 1934 1,983,780

uuirao STATES PATENT OFFlCE PISTON John M. Shimer, Wllkinlbnrg, Pa., auignor to Wilson-Snyder Manufacturing Corporation, Braddock, 2a., a corporation of Pennsylvania Application October 20, 1931, Serial No. 569,887 8 (Cl. 309-31) The present invention relates to means, such piston and ring; and I, therefore, make the pathas packing for sealing a piston, which is to be along which fluid would have to pass circuitous, used in a pump for pumping fluids. One obso as to reduce the chances of leakage to a minject of my invention is to provide a packing or imum. The joint between the shoulder of the sealing ring which tends to tightly lit the cylinpiston and the ring takes the iorm herein of a 5 der wall and which is securely mounted on the labyrinth. The cross-section of a joint formed piston. in accordance with the principles of my invention A further object of my invention is to provide might have an s-shaped juncture line; but in the an improved packing ring which is'durable, and particular embodiment selected for illustration.

10 which is effective in sealing against the passage the juncture is made with sharp comers. The 10 of fluid past the piston. Further objects will belabyrinth might be otherwise described as a come apparent during the course of the ensuing tenon and mortise joint which permits a rib 23 description, and will be more particularly pointed on the piston to slide into a groove in the ring, out in the accompanying claims. and a rib 24 on the ring to slide into a groove on In the accompanying drawings, I have shown the piston. 5 for purposes of illustrating my invention, and not As shown more particularly in Fig. 2 of the as limiting the same, one embodiment which the drawings, the piston 11 is provided with ,a pluralsame may assume. ity of projections or lugs 25; and when the ring Fig. 1 is a longitudinal sectional view of a is assembled with the piston, the lugs 21 on the 3;) piston provided with rings for sealing the piston ring enter between the projections 25 onthe pisagainst leakage along the cylindrical surface 01 ton. At the same time, the portions of the ring the same; and piston, which constitute the labyrinth, inter- Fig. 2 is an end view taken from the right of engage. The ring is then rotated so as to bring Fig. 1 of the piston, a portion of the piston and the lugs 21 behind the projections 25. The ring '5 n being r n aw y t illus rate a detail; is now locked to the piston; but in order to pre- 25 Fi 3 i n n V w f n f the Pi n rin s; vent separation of the two, it is desirable to pre- Fig. 4 is a sectional view on the line IV-IV of vent such rotation 01. the ring that the lugs 21 Fig. 3. are no longer behind the projections 25. A spring In the embodimen which I at p t prefer, -metal detent 27 is fastened by a screw 28 to the 30 the piston 11 s ou t on t tapering p tion piston 11. This detent is principally contained 30 12 of a piston rod 13. A pair 0! nuts 14 hold the within a rec s 29 in the piston; and when the piston n the n of the r T Piston is ends of the detent are sprung inwardly, the entire formed with a cylindrical surface 1 whi h i detentis contained within the recess 29. Normalsdapted to Slide in the re of a cylinder. Ad- 1y, however, the ends or the detent extend outjacent the cylindrical surface 15, the piston is wardly beyond the recess 29; and spring back to cut aw y o p v a shoulder against w c this position 11 released. The recess 29 is in salinem y u a P k n r If a piston is to ment with the lugs 21 when the ring is in opernsed in a S gl a n p but one Piston ring ative position on the piston, as is evident irom and but one shoulder is necessary. In the em- Fig. 1, During th assembling f the ring with bodimeht illustrated in the drawings, h Piston the piston, 9. lug 21 is forced over the detent 27, 40 is intended for a double-a in p p and thus flexing the ends inwardly. When the ring cordingly the piston is cut away on both sides of is t t t bring t lugs 21 behind t projecth y in u a 5, thus providing tions 25, the ends or the detent are released and p s d h l sprung into the opening between two lugs 21, as

Since each of the p ckin rings is of substahs is evident in Fig. 2. The detent is thus operative tially the same construction, a description of one t prevent such t t 1' th ring as ill it w sufilee for both- As shown in Figs- 3 and 4, the same to become loosened from the piston. th p kin n is of rubber, the body Portion 20 It is desirable that a portion of the ring be elasof the ring being of hard rubber or composition t d flexible enough to yieldably engage the which does not flex and has rigidity of a high walls of the cylinder within which the piston 11 50 order. This body portion 20 is intended to be i t r ciprocate. The ring might be made in moun ed n e p n and i provided with a two portions, one of which is stiff and hard, and p u a ty f nward y projecting p rt ns or u s the other of which is flexible to act as the sealing 21 for locking the ring to the piston. It is highly portion of the ring. I find it advantageous to desirable to prevent leakage of fluid between the te m the ring as an integral member; an by 66 making the ring of rubber and vulcanizing the body portion harder than the sealing portion,

I am able to provide a ring which is durable and is yet highly efficient in sealing against leakage past the piston.

I prefer to taper the sealing portion of the ring, as indicated in Fig. 4 of the drawings. When this tapered portion is the leading edge of the piston, the fluid pressure in that end of the cylinder has an outwardly di-rected component which forces this leading edge into sealing engagement with the walls of the cylinder.

I have discovered that while this tapering of the leading edge is desirable, it is not sufficient to ensure against leakage; and I have furthermore discovered that if, before insertion in the cylinder, the leading edge of the ring is oversize so that its periphery must be made smaller before it can be gotten into the cylinder, effective sealing is accomplished. Due to the soft rubber portion of the ring being oversize, this portion is crowded into engagement with the walls of the cylinder. During the compression stroke, the bevel assists the crowding action of the leading edge in effecting sealing. During the suction stroke, there is a tendency for the beveled portion of the ring to suck away from the cylinder walls. I have discovered that by making the flexible portion of the ring oversize, as indicated in Figs. 1 and 4. this portion is crowded against the cylinder walls so that they are not drawn away from these walls even during the suction stroke.

By making the ring non-uniform, the hard rubber portion resists wear and tear, and the life of the ring is extended. This improvement, in durability, does not interfere with the efficiency of the ring in sealing. In fact, by making the flexible portion oversize, I have much improved the sealing efficiency of the ring.

While I have specifically illustrated and described the preferred embodiment of my improved piston and packing ring, it is to be understood that the invention is not so limited, but may be otherwise embodied and practiced within the scope of the following claims. 4

I claim:

1. A pump piston comprising a body comprised of substantially non-fiexing material having a laterally projecting circumferential collar thereon and a detachable packing ring comprised in part of non-flexing material and in part of fiexing material surrounding the body, said collar and the non-flexing portion of the ring having inteizengaging mortise and tenon portions to form an annular labyrinth sealing the junction between the collar and the ring.

2. A pump piston comprising a body comprised of substantially non-flexing material having a laterally projecting circumferential collar thereon and a detachable packing ring comprised in part of non-flexing material and in part of flex-.

ing material surrounding the body, said collar and the non-flexing portion of the ring having interengaging ribs and grooves to form an annular labyrinth sealing the junction between th collar and the ring.

3. In combination, a piston having a cylindrical surface for sliding in the bore of a cylinder and an annular shoulder at one end of said cylindrical surface. and a detachable packing ring comprised in part of non-flexing. material and in part of flexing material disposed on said piston against the said shoulder, the non-flexing portion of said ring forming a continuation of the cylindrical surface of the piston, the abutting surfaces of said ring and piston carrying tenon and mortise joints forming an annular labyrinth sealing the junction therebetween.

4. In combination, a piston having a cylindrical surface for sliding in the bore of a cylinder, an annular shoulder at one end of said cylindrical surface, a plurality of projections spaced from the shoulder, and a detachable packing ring comprised in part of non-flexing material and in part of flexing material disposed on the said piston against the said shoulder, the non-flexing portion of said ring having inwardly projecting portions for interlocking with the projections of the shoulder by relative rotary movement between the piston and ring, and the said shoulder and the non-flexing portion of the ring having interengaging portions to form an annular labyrinth sealing the junction between the shoulder and ring.

5. In combination, a piston, a packing ring, said piston and packing ring being provided with means for interlocking the same by relative rotary movement, and a yieidable leaf spring member carried by the piston for holding the packing ring in interlocked position.

6. In combination, a piston having recesses, a continuous packing ring having projections receivable in said recesses by relative rotary movement between the piston and ring, and a yieldable leaf spring member carried by the piston for holding the ring against rotation to releasing position.

7. In combination. a piston having a plurality of projections, a packing ring having inwardly extending lugs for interlocking with the projections by relative rotary movement between the piston and ring, and a yieldable leaf spring member carried by the piston for engaging a lug of the ring when the ring is in interlocked position.

8. In combination, a piston having a plurality of projections, a packing ring comprised of rubber formed with a body portion of relatively non-flexing rubber having inwardly extending lugs for interlocking with the projections by relative rotary movement between the piston and ring and an annular flange portion integral with the body portion comprised of relatively flexible rubber adapted to laterally extend beyond the peripheral surface of the body portion, and a leaf spring member carried by the piston in position to engage in the space between lugs on the ring when the ring is in interlocked position.

JOHN M. SHIMER. 

